A range of site equipment accessories—such as water pumps, air compressors, electric generators, power washers, vibrating pokers, chippers, shredders, vacuums, plate compactors etc—require a power drive, conventionally provided by a portable power unit in the form of a utility single cylinder engine. Current procedure is that it is necessary to hire, or buy, a variety of plant or equipment accessories, each of which is provided with its own utility engine which is often the most expensive component of the accessory. Consequently, purchasing, secure storing and maintaining a number of these accessories can place large financial, logistical and time burdens on their owner.
Typically, an average builder may purchase a number of utility engine powered accessories—for example, a generator, water pump and power washer, preferably with a “branded engine”, i.e. a Honda or Mitsubishi etc. Usually the cost of a “branded engine” 2.5 kVA generator and 3″ water pumps is of the order of £500+. Similar power washers can cost £600+. Overall, the cost of purchase can reach £1500-£2000.
The value of these accessories also requires secure overnight storage to deter theft.
The advantage of having a single, readily attachable and detachable power unit to drive a range of accessories has been recognized for decades. One proposal for carrying out this principle is described in U.S. Pat. No. 5,907,970. However, a critical aspect for success is the accurate alignment of a power output shaft of the engine and a power input shaft of the accessory to be driven, bearing in mind that connection and disconnection will normally be effected at building sites, and not in an assembly shop with the aid of jigs etc, otherwise an unacceptably short service life will result. Another proposal is described in U.S. Pat. No. 4,269,075. In addition, prior constructions have incorporated a dog clutch rather than a friction clutch, it being guesswork as to whether the teeth of the two clutch halves will mesh upon the accessory being presented to the power unit, or will foul one another, possibly, requiring repeated withdrawal and partial rotation of one clutch half with a view to achieving meshing. However, due it is believed to the difficulties and frustrations of satisfactory “on-site” connection, no system has to date, been marketed, as far as Applicants are aware.